Issues using CGA converter with 1942 board

[Mental]

I'm attempting to hook a Williams/Capcom 1942 board up to an LCD monitor using one of those GBS-8200 cga to vga converter boards. It displays, but it is shaking vertically (left to right on the game), very badly.

I've read that those converters are hit and miss when it comes to older PCBs. Is there a simple solution to get this working? Maybe a different type of converter? or a sync cleaner?

[grantspain]

have you tried holding DOWN/AUTO to auto scan?

[Mental]

have you tried holding DOWN/AUTO to auto scan?

No, just pressing it. It didn't help. Does holding do something different?

[grantspain]

have you tried holding DOWN/AUTO to auto scan?

No, just pressing it. It didn't help. Does holding do something different?

you have hold both the "down" and "auto" button to autoscan frequency,not sure if you do it on power up or during normal operation-i think you just hold both buttons for a few seconds(been a while since i worked on one of these)

[Mental]

No, just pressing it. It didn't help. Does holding do something different?
[/quote]
you have hold both the "down" and "auto" button to autoscan frequency,not sure if you do it on power up or during normal operation-i think you just hold both buttons for a few seconds(been a while since i worked on one of these)
[/quote]

Pressing it seems to rescan (no change). Holding it seems to reset to defaults (no change).

It either can't sync properly with old games, or the sync out of the 1942 is wonky somehow.

I've discovered another guy that seems to have the same issue with a Galaga hooked up to an 8200. Not sure if it's ok to post links to other forums ("GALAGA - some sync problem"). I wonder if this is a common problem.

[grantspain]

if you mentioned an snk or namco game then i know they have a slightly wierd sync signal and some monitors need a 5k resistor from video ground to vertical sync
bit stumped with this one,could even be a faulty converter board

[Mental]

if you mentioned an snk or namco game then i know they have a slightly wierd sync signal and some monitors need a 5k resistor from video ground to vertical sync
bit stumped with this one,could even be a faulty converter board

I had to go by Starburst this afternoon and they kindly threw it on the test bench for me. Everything looked 100%. I think those converters just can't handle some old boards very well.

[Mental]

Update: I got the image to stabilize once, but for some reason only once, by turning the voltage down on the power supply as low as it would go. The image dimmed slightly, but no more shaking. Next step, try a different power supply and see how it helps.

[grantspain]

are you using video ground from pin 14 of the edge connector or just power supply/switch ground?

[Mental]

are you using video ground from pin 14 of the edge connector or just power supply/switch ground?

I've tried both ways. It didn't make a difference. I think on the 1942 board, they both come off pretty much the same ground plane.

[Mental]

Update: I just tried with a different power supply, and an updated VGA converter, but still get the vertical shaking. Is it possible the board isn't outputting the video 100%?

[grantspain]

only way you could prove it is by trying a different game board

[Mental]

I just hooked the board up to a new LCD from Nieman Displays and there is no shaking at all. It was also fine on a CRT on the test bench at Starburst. Lesson learned, those cheap Chinese VGA converters are only so useful.